'Forehead' in the Bible

But the house of Israel will not hearken unto thee; for they will not hearken unto me: for all the house of Israel are of hard forehead and of a stiff heart.

Behold, I have made thy face hard against their faces, and thy forehead hard against their foreheads.

As an adamant harder than flint have I made thy forehead: fear them not, neither be dismayed at their looks, though they are a rebellious house.